Device adapted to dosing pasty substances

ABSTRACT

A device for applying fluid having a pasty consistency is provided. The present invention relates to a device for applying brazing paste manually or by means of a robotic arm, having an elastically deformable conduit and a drive spindle.

CROSS REFERENCE TO RELATED APPLICATION

This Application is a 371 of PCT/EP2017/072816 filed on Sep. 12, 2017which, in turn, claimed the priority of European Patent Application No.16382421.2 filed on Sep. 13, 2016, both applications are incorporatedherein by reference.

OBJECT OF THE INVENTION

The present invention relates to a device adapted to dosing fluid havinga pasty consistency. Particularly, the present invention relates to adevice for applying brazing paste manually or by means of a robotic arm,comprising an elastically deformable conduit and a drive spindle.

BACKGROUND OF THE INVENTION

In the joining process known as brazing, the filler material forperforming it, generally a metal powder with a melting point below themelting temperature of the part to be joined, can be applied on or closeto the joint that is to be welded together with binders, fluxes and/orother additives, such that they form a fluid having a pasty consistency.This fluid, which must be a homogeneous mixture so that the applicationthereof is effective, usually has a high viscosity and, since the powderis abrasive, specific tools with abrasion-resistant materials arerequired.

This joining process is widespread in the industry, particularly in theautomotive sector, as a result of the possibility of being automated andthe capacity thereof to join a plurality of parts with a single passagethrough the furnace, so the adaptation thereof to mass productionequipment is advantageous.

Patent document JP 2015529397 A describes a solder paste supply devicecomprising two cylindrical chambers with pistons and a bottle-neckconnection part communicating both chambers further comprising a nozzlefor applying the solder paste. This device requires both pistons to movein one direction or another for depositing the fluid, and said pistonsmust furthermore be reloaded every time their load runs out.

Patent document US 2016031029 A1 describes a device and a method forjetting particles of viscous material on a workpiece. To achieve thiseffect, the device has a feed screw moving the fluid along a feedconduit to a plunger jetting the material through the nozzle. This modenot only requires rotational movement of the feed screw but alsoalternative movement of the plunger. Furthermore, this device onlyallows applying the viscous material discontinuously as a result of themovement of the plunger.

In any of these inventions of the state of the art, those movingportions with sliding surfaces which are in contact with the paste aresubjected to abrasion by the metallic powder.

None of the preceding devices can duly solve all the existing problems.Particularly, none of them allows applying a high viscosity abrasivesubstance, such as the case of brazing paste, continuously or atintervals by means of a versatile tool that can be handled by anoperator or adapted to the arm of an industrial robot such that it canefficiently dose abrasive pastes in automated processes.

DESCRIPTION OF THE INVENTION

The present invention provides an alternative solution to theaforementioned problems which can be overcome by means of a device fordispensing a high viscosity fluid abrasive substance comprising thecombination of a drive spindle and an elastically deformable conduit forfeeding the fluid.

In a first inventive aspect, the invention provides a device adapted todosing fluids having a pasty consistency, comprising:

-   -   a first base with an inlet for the fluid;    -   a second base, spaced from the first base, with an outlet for        the fluid;    -   an elastically deformable tubular conduit with an end in fluid        communication with the inlet and with the opposite end in fluid        communication with the outlet;    -   a rotating spindle with at least one spiral thread for driving        the fluid housed in the tubular conduit, with an end of the        spindle rotationally attached to the first base and the opposite        end of the spindle rotationally attached to the second base,        this spindle being adapted for pressing on the tubular conduit        with at least one part of its spiral thread;    -   a support backing of the tubular conduit such that at least the        segment of tubular conduit adapted for being in contact with the        spindle is located between the spindle and the support backing;    -   an actuating shaft integrally attached to the spindle for        driving the rotation of said spindle.

Throughout the present document, “fluid having a pasty consistency”,“fluid” or “paste” will be understood as any fluid material having aviscosity that is possibly higher than that of water in environmentalconditions, being particularly valid for gels, amalgams or fluids with acomparable viscosity. Notwithstanding what has been indicated above, thedevice will also be able to dispense fluid of other types, regardless ofthe physical properties thereof.

The term “elastically deformable tubular conduit” generally describesany element which allows fluid communication between two pointsseparated from one another, with elastic capacities allowing it tochange shape, for example, restricting or even completely closing theopening of its inner cavity by applying pressure on its outer wallswithout negatively affecting the integrity of the element.

It is understood that the “spindle” is an essentially cylindricalelement on the side of which there is one or more elements, which willbe referred to as threads, projecting from the level defined by theradius of the cylinder, the function of the spindle being to rotatealong the length of its longitudinal axis.

The element referred to as “support backing” must be interpreted in thisdescription as the element that serves as a support and is adapted forreceiving a force by means of the support. Particularly, the tubularconduit is located between the support backing and the spindle such thatthe force applied by the spindle on the tubular conduit is supported bythe support backing located on the other side of the tubular conduit.Furthermore, it can perform additional functions, such as serving as amount for the conduit or closing the cavity of the spindle.

In a particular embodiment, the support backing comprises a partialhousing for the tubular conduit to allow the support of the tubularconduit on said support backing and to allow the contact of the spiralthread with the tubular conduit such that the partial housing securesthe position of the tubular conduit upon receiving deformation strainfrom the spindle.

Advantageously, the support backing allows positioning the tubularconduit in relation to the bases of the device and to the spindle,fixing the ends of the assembly and making the contact between thethreads of the spindle and the walls of the tubular conduit possible.

In a particular embodiment, the tubular conduit and the support backingare integrated in one and the same part.

In a particular embodiment, the tubular conduit and the support backingare independent parts.

Advantageously, the tubular conduit is configured for being able to beeasily taken out, as an independent part or together with the supportbacking.

In a particular embodiment, the support backing is made of anelastically deformable material. As a result of this feature, thesupport backing can absorb the stress produced by the pressure of thethreads on the tubular conduit and distribute it throughout thestructural elements of the device in contact with the support backing.In this embodiment, the support backing is more rigid that the tubularconduit, for example, by means of a thicker wall.

In another particular embodiment, the dosing device comprises a shellattached to the first base and to the second base.

Advantageously, the shell constitutes a protective structural elementwhich allows keeping the elements forming it together, distributingstress and preventing the presence of foreign bodies. The shell, inaddition to being part of the structural assembly formed by both bases,can perform additional functions such as the function of containing alubricating fluid to reduce the friction between the spindle and theelastically deformable conduit as a result the sliding of the threadsforcing the fluid having a pasty consistency to move forward.

In a particular embodiment, the first base, the second base, or both,are integral part of the shell enclosing the space housing at least thespindle and the tubular conduit. It is therefore possible to streamlinethe manufacture and the use of the device, reducing the number ofdifferent elements forming it.

In another particular embodiment, the shell comprises one or more screwstransversely threaded to said shell, with the head accessible from theoutside, the end of which reaches the support backing to act as atemporary support for the adjustable spindle.

The position of the support backing or the tubular conduit with respectto the spindle can advantageously be adjusted, or the degree ofrestriction of the tubular conduit can advantageously be regulated tocontrol the fluid flow rate, by regulating the position of thetransverse screws which are in contact with the support backing ordirectly in contact with the tubular conduit such that they act as asupport of the support backing or of the tubular conduit.

In yet another particular embodiment, a plate interposed forhomogenizing the force of the screws on the support backing is arrangedbetween the threaded screws and the support backing.

Advantageously, the plate is a rigid element which allows distributingthe stress applied by the screws along the length of the tubularconduit.

In a preferred embodiment, the shaft is flexible, connecting an actuatormotor and the spindle to allow for the manual orientation of saiddevice.

The use of a flexible shaft is particularly advantageous as it allowstransmission of torque to the spindle regardless of the position of thedevice in relation to the source of the torque. The shaft can thereforebe used manually by an operator a certain distance from the source ofthe torque.

In another particular embodiment, the shaft is rigid, connecting anactuator motor and the spindle to allow for the mounting of said deviceon a machine. Advantageously, the rigid shaft-operated device can bemounted on a mount of a machine tool or a robotic arm.

In another particular embodiment, the spindle has a discontinuous spiralthread for driving the fluid discontinuously.

The mentioned discontinuities of the spindle, which can be, for example,notches or sections eliminated from the thread arranged in spiral aroundthe spindle, allow the fluid to flow at regular intervals, which may beapplicable in automated production processes.

In a particular embodiment, the spindle has a spiral thread with acurved section. Advantageously, the mentioned spiral thread of thespindle allows transforming the torque of rotation of the spindle into aforce normal to the flank of the thread. Depending on the profile of thethread, it applies on the tubular conduit a force which, according toits direction can be broken down into two components, a radial componentand a longitudinal component, the longitudinal component beingresponsible for moving the fluid. A thread with a curved section allowscontact with the conduit to take place gradually, obtaining as a resulta smooth fluid movement. The smooth shape of a curved section alsoincreases the service life of the elastically deformable conduitdeformed by said thread.

In another embodiment, the invention provides a system for dosing fluidshaving a pasty consistency, comprising a device according to any of thepreceding embodiments and a drive motor for driving the shaft which canbe regulated by the user.

In the present document, the drive motor for driving the shaft isinterpreted as any source of drive torque capable of transmitting powerto the shaft of the spindle, the power level and/or rotational speedthereof preferably being able to be regulated, such as an electricmotor, for example.

In a preferred embodiment, the system comprises a fluid drive unit forincreasing the pressure of said fluid at the inlet.

Advantageously, the fluid drive unit allows maintaining a fluid pressurelevel which makes it easier for the fluid to enter the device by makingthe passage of the fluid through the device easier, even for highviscosity fluids. Nevertheless, the drive unit does not establish theflow rate of the paste to be supplied, rather the assembly formed by thespindle and the elastically deformable conduit is what determines theflow rate of the paste, particularly by means of the rotational speed ofthe spindle and the spiral thread pitch of the spindle.

In another particular embodiment, the fluid outlet comprises aninterchangeable applicator. Advantageously, the applicator allowsdepositing the fluid on a particular point of the surface of a part, thedimensions of the section of the applicator determining at the endthereof the amount and shape of the deposited material. In a simpleexample, this applicator can be a simple cylindrical, straight orconical conduit.

In a last particular embodiment, the device comprises a mechanical,electromagnetic or pneumatic clamp to keep the support backing attachedto the shell.

DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages of the invention will bemore clearly understood based on the following detailed description of apreferred embodiment, provided only by way of an illustrative andnon-limiting example in reference to the attached drawings.

FIGS. 1a-1b show a first embodiment of the device, including a sectionview.

FIGS. 2a-2c show a second embodiment of the device, including twosection views.

FIGS. 3a-3b show two views of the device in an operating position.

DETAILED DESCRIPTION OF THE INVENTION

According to the first inventive aspect, the present invention relatesto a device for dosing or applying fluids having a pasty consistency,particularly for applying brazing paste on the contact surface betweentwo parts to be welded together. In addition to being abrasive, thismaterial usually has a high density and viscosity. For this reason, itis not possible to use conventional devices for applying weldingmaterial in the form of gels or pastes or these devices will have ashort service life as a result of wear. As an additional advantage, thedevice is also capable of dispensing other fluids, regardless of theirdensity or viscosity.

In a first preferred embodiment of the present invention shown in FIGS.1a and 1b , the device comprises an elastically deformable cylindricaltubular conduit (5) through which the brazing paste flows, and a spindle(3) driven by a spiral drive shaft (8) arranged parallel to the tubularconduit (5) and interfering it, such that the threads (3.1) of thespindle (3) press on the tubular conduit (5) obstructing it partially orcompletely, and such that when the spindle (3) rotates, the spiralthreads (3.1) push the pressed conduit segment in the axial direction,causing the movement of the paste contained inside the tubular conduit(5).

A stator, mount or support backing (4) holds the tubular conduit (5) toprevent it from moving and serves as a support against the pressure andstress applied by the threads (3.1) of the spindle (3). As can be seenin FIG. 1a , in this embodiment the support backing (4) is in turnsupported on a shell (9), a structural element containing and protectingthe components of the device, serves as a support for the components andallows an operator to hold the device with their hand or another type ofmount. The ends of the shell (9) are closed by two bases, the first base(1) and the second base (2), having in this embodiment the additionalfunction of fixing the tubular conduit (5) at both ends, allowing theentry and exit of the paste through the inlet (6) and the outlet (7),allowing the connection of the drive shaft (8) acting on the spindle(3), serving as a rotary support for the spindle through a bearing, andholding an applicator (10) or nozzle. The bases (1, 2) are attached tothe shell (3) by means of screws, and they can be removed to access theinside of the device, for example, for repairing or for replacing thetubular conduit (5). Additionally, the empty space formed between theshell (9) and the other elements of the device can be filled with alubricating element, for example, glycerin, to reduce the frictionbetween the spindle (3) and the tubular conduit (5).

There is supported on the portion of the support backing (4) arranged onthe side opposite the spindle (3) a flat plate or sheet interposedbetween the support backing (4) and a series of screws arranged in theradial direction with respect to the shaft of the spindle (3). Itsfunction is to regulate the position of the flat plate which presses onthe support backing (4) and allows regulating the position of thetubular conduit (5) with respect to the spindle (3) and the degree ofrestriction of the conduit (5).

The first base (1) has an inlet (6) for the paste in fluid communicationwith the tubular conduit (5); this inlet (6) comprises an anchoringelement for holding the tubular conduit (5) on the inner face of thefirst base (1), and a connection point with the paste feed conduit onits outer face. This connection must be suitable for supportingpressures higher than the environmental pressure and withstandingtensile strain, bending strain, etc. produced by the use of the devicein different positions. At another point of the first base (1), anopening allows the access of an actuator or a flexible drive shaft (8)to transmit torque to the shaft of the spindle (3), this attachmentbeing able to be a mechanical-type attachment by means of a shaft with akey, by means of a magnetic coupling or through a gear train, forexample.

Like in the first base (1), the ends of the shaft of the spindle aresupported on the second base (2), such that they can rotate freely bymeans of bearings. The second base (2) comprises an outlet (7) in fluidcommunication with the tubular conduit (5), configured for coupling anapplicator (10), and an anchoring for the front end of the tubularconduit (5). The main function of the applicator (10) is to project thepaste flow onto a part, with the desired shape and size. Said applicator(10) can be a long and narrow conduit with an end that can be connectedto the second base (2) by screwing or snap-fitting. An additionalfunction of the applicator (10) and of the front end of the tubularconduit (5) is to form an intermediate storage volume to produce acontinuous paste flow rate at the outlet of the applicator (10).

The material of the tubular conduit (5) is preferably an elasticallydeformable material that is resistant to abrasion and repetitiveshearing strains, such as silicone, polyurethane or a similar material,for example. Not reacting chemically with the paste, being lightweight,cost-effective and easy-to-manufacture are other desirable features ofthe material.

The cross section of the tubular conduit (5) must be such that it allowsthe paste to flow through the inside thereof and has a high resistant toshearing strains applied by the spindle (3) in the radial direction withrespect to the spindle (3) and to tensile strain in the axial direction.Furthermore, it must make the fixing thereof to the support backing (4)or the shell (9) easier. A possible section of the tubular conduit (5)according to a transverse plane is essentially circular, hollow, with athicker wall in the portion that fits in the support backing (4), and athinner wall in the portion in contact with the spindle (3).

The spindle (3) must be made with a dimensionally stable resistantmaterial that is harder than the tubular conduit (5) and with a reducedlevel of friction. One possibility is to make said spindle with polishedmetal, steel or lightweight aluminum alloys, composite materials orplastic materials can also be used, for example. Additionally, onedesirable feature is for the spindle to be lightweight so that it can becomfortably handled by an operator, or so that it can be coupled to arobotic arm without creating high inertias.

In a second embodiment shown in FIGS. 2a and 2b , the tubular conduit(5) is part of the support backing (4), being partially or completelyintegrated in said element during manufacture or by means of assemblycombining two or more parts. For example, the tubular conduit (5) andthe support backing (4) can be made by joint injection using differentmaterials or manufactured with the same material.

In this embodiment, the support backing (4) is configured as a coverclosing a cavity housing mainly the spindle (3). Along the perimeter ofthe opening established by the cavity, the support backing (4) comprisesa sealing gasket (14) manufactured with an elastically deformablematerial, for example, rubber, which allows closing in a leak-tightmanner the cavity of the spindle (3), both to prevent the lubricant fromleaking out through the joint, and to prevent dirt, dust or foreignbodies from entering said cavity.

FIG. 2b shows an exploded view of the assembly in which the spindle (3),the support backing (4), the tubular conduit (5) and other elements arenot in their normal operating position to allow better viewing theassembly. It can be seen in this FIG. 2b that in this embodiment thesupport backing (4) has a prism shape, with a section having a circularsector, and a gap configured to allow partially housing the spindle (3),allowing its rotation and the contact between the tubular conduit (5)and the threads (3.1) of the spindle (3), the tubular conduit (5) beingarranged parallel to the longitudinal axis of the prism. Furthermore,the support backing (4) is configured for fitting in a gap of the shell(9) housing it. This gap is particularly adapted to make it easier totake out the support backing (4) with the tubular conduit (5) for quickreplacement. In this case, the bases (1, 2) of the device are integralparts the shell (9) and perform a structural function, joining the restof the elements and serving as a mount and protection for said elements;considering its function as a mount for the spindle (3), the bases (1,2) comprise a set of needle or roller bearings (13.1, 13.2), on whichthe ends of the shaft of the spindle (3) are supported. It isadvantageous in this case to introduce a rear cover (9.1) protecting thepaste inlet (6) and the access of the shaft (8), in addition to allowholding a feed connector (12).

The assembly of the support backing (4) with the tubular conduit (5) isfixed to the device by means of a closure element, for example a clamp(11) secured by means of a threaded bolt or the like that envelopes partof the shell (9) and the support backing (4), such that the device canwork safely without the support backing (4) moving from its operatingposition.

FIG. 2c shows a cross-section view in which the arrangement of thespindle (3) with respect to the tubular conduit (5) and the supportbacking (4) can be seen more clearly. The position of the supportbacking (4) is such that it almost completely surrounds the tubularconduit (5), only exposing the portion pressed by the threads (3.1), butwithout hindering the movement of the spindle (3). The shell (9), incontact with the sealing gasket (14) of the support backing (4) closesthe cavity of the spindle (3) in a leak-tight manner, and the assemblyis attached in the operating position by means of the clamp (11) whichis closed with a locking bolt (15).

According to another embodiment, the system comprises in addition to thedosing device, a drive motor applying drive torque to the spindle (3).This motor can be an electric motor, a pneumatic motor or another typeof motor, but it is desirable for the power, speed and direction ofrotation of said motor to be controllable by the operator. The drivemotor according to one embodiment is connected to the device through aflexible shaft (8) which allows transmission of torque from any positionand orientation, or by means of a rigid shaft (8) indicated for staticapplications or in which the device is mounted on an articulated mount,such as on a robotic arm, for example. Alternatively, according toanother embodiment power is transmitted by means of a pressurized fluid,in which case the device would comprise a turbine for obtaining thedrive torque of the pressurized fluid.

The paste is supplied to the device through the feed connector (12)which, depending on the particular application, is carried out by meansof a vessel or by means of a continuous pumping apparatus. In the firstcase, a pressurized vessel loaded with paste which must be replenishedonce it runs out is used. If a pumping apparatus is used, it isdesirable for the feed connector (12) to be resistant to abrasion andhigh pressures; the apparatus will possibly have a system formaintaining the pressure of the fluid above the atmospheric pressure forthe purpose of making it easier to feed the paste, although any of thepossible paste feeding modes can be carried out at atmospheric pressure,resorting exclusively to the suction produced by the spindle (3)-tubularconduit (5) assembly for moving the paste.

In one embodiment, the feed connector (12) comprises a retention spring(12.1) and a fixing rod (12.2), having the function of securing theconnection between the tubular conduit (5) and the pressurized pastesupply conduit. To that end, the feed connector (12) is introducedthrough the inlet (6) of the device, while the fixing rod (12.2) slidesat the same time along a fixing groove (9.2) made in the axial directionon the side of the shell (9). Said fixing groove (9.2) has a finalportion forming a right angle, such that when the fixing rod (12.2)reaches said final portion, it is possible to cause the rotation of thefeed connector (12), such that the fixing rod (12.2) slides along thefinal portion of the fixing groove (9.2) and is locked in said position.The retention spring (12.1) in turn assures the fit between the tubularconduit (5) and the feed connector (12) allowing the paste to flowwithout leaking.

The system furthermore allows a quick disassembly method which can beperformed in four phases using only one tool. Said process comprises thephases of:

-   -   a) taking out the locking bolt (15) with a screwdriver or a        comparable tool;    -   b) removing the clamp (11);    -   c) removing the feed connector (12) by means of rotating the        fixing rod (12.2) and moving it in the longitudinal direction;    -   d) taking out the support backing (4).

Once the support backing (4) has been taken out, it can be replacedentirely if necessary, cleaning tasks can be performed, the tubularconduit (5) can be replaced, the sealing gasket (14) can be replaced,the lubricant can be replenished, the spindle (3) can be replaced, etc.The disassembling operation requires the application of thedisassembling steps carried out in reverse order.

FIG. 3a shows the profile of a device assembled and in an operatingposition. This figure shows the clamp (11) and the fixing rod (12.2)inserted in the fixing groove (9.2). The mechanical drive of the device,the shaft (8), and the connection point of the pressurized conduit, thefeed connector (12), can be seen. FIG. 3b shows the device also in theoperating position from a point of view rotated 90 degrees with respectto FIG. 3a , which allows seeing the essentially cylindrical shape ofthis embodiment. This shape is particularly advantageous so that anoperator can hold the device comfortably with only one hand and use it,for example, in an assembly line from several positions. Additionally,the device can adapt a “pistol”-type handle so that it can be handledwithout having to bend the wrist.

The invention claimed is:
 1. A device adapted to dosing fluids having apasty consistency, comprising: a first base with an inlet for the fluid;a second base, spaced from the first base, with an outlet for the fluid;an elastically deformable tubular conduit with an end in fluidcommunication with the inlet and with the opposite end in fluidcommunication with the outlet; a rotating spindle with at least onespiral thread for driving the fluid housed in the tubular conduit, withan end of the spindle rotationally attached to the first base and theopposite end of the spindle rotationally attached to the second base,this spindle being adapted for pressing on the tubular conduit with atleast one part of its spiral thread; a support backing of the tubularconduit such that at least the segment of tubular conduit adapted forbeing in contact with the spindle is located between the spindle and thesupport backing, wherein the tubular conduit and the support backing areintegrated in a same part, wherein the support backing is made of anelastically deformable material; and an actuating shaft integrallyattached to the spindle for driving the rotation of said spindle whereinthe part integrating the elastically deformable tubular conduit and thesupport backing are made from a joint injection of different materialsor same materials, the support backing comprises a partial housing forthe tubular conduit to allow the support of the tubular conduit on saidsupport backing and to allow the contact of the spiral thread with thetubular conduit.
 2. The device according to claim 1, wherein the tubularconduit and the support backing are independent parts.
 3. The deviceaccording to claim 1, comprising a shell attached to the first base andto the second base.
 4. The device according to claim 3, wherein theshell comprises one or more screws transversely threaded to said shell,with the head accessible from the outside, the end of which reaches thesupport backing to act as a temporary support with respect to theadjustable spindle.
 5. The device according to claim 1, wherein thefirst base, the second base, or both, are integral part of a shell. 6.The device according to claim 1, wherein the shaft is flexible,connecting an actuator motor and the spindle to allow for the manualorientation of said device.
 7. The device according to claim 1, whereinthe shaft is rigid, connecting an actuator motor and the spindle toallow for the mounting of said device on a machine.
 8. The deviceaccording to claim 1, wherein the spindle has a discontinuous spiralthread for driving the fluid discontinuously.
 9. The device according toclaim 1, wherein the spindle has a spiral thread with a curved section.10. The device according to claim 1, comprising a mechanical,electromagnetic or pneumatic clamp for maintaining the support backing.11. A system for dosing fluids having a pasty consistency comprising adevice according to claim 1, the system further comprising: a drivemotor for driving the shaft which can be regulated by the user; a fluiddrive unit for increasing the pressure of said fluid at the inlet; orboth the drive motor and the fluid drive unit.